Browse Prior Art Database

Magnetically Striped Document

IP.com Disclosure Number: IPCOM000074704D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Denk, HH: AUTHOR

Abstract

A document having a magnetic stripe that is always moved in one predetermined direction past a recording head can have its signal strength enhanced. This is achieved by aligning the major axis of orientation of the magnetic particles at angles which approximate those of the field lines emanating from the trailing edge of the gap of the recording head with which the document is to be used.

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Magnetically Striped Document

A document having a magnetic stripe that is always moved in one predetermined direction past a recording head can have its signal strength enhanced. This is achieved by aligning the major axis of orientation of the magnetic particles at angles which approximate those of the field lines emanating from the trailing edge of the gap of the recording head with which the document is to be used.

A magnetic coating is applied as a narrow fluid stripe 1 (see A, B) at station 2 to substrate web 3. While still fluid, stripe 1 passes in a predetermined direction between and straddles at least one set of thin (e.g., 0.001') brass shims 4. Each set of shims 4 rides on web 3 and spaces above 1 a corresponding ring magnet 5 having a very small gap (less than 0.010''). Each magnet imparts a nonhomogeneous field to 1 while it is still fluid and orients the magnetic particles at angles approximating the head gap trailing field of the recording head. The small gap orients the magnetic particles, as shown schematically in C, by slope drawn tangent to contour lines 6 of equal field strength measured at various distances from the trailing edge of gap 7 of recording head 8; e.g., slopes S(1), S(2), S(3) at H/Ho of 0.5, 0.4 and 0.3, respectively.

When web 3 is later fed in the predetermined direction past recording head 8, signal strength is enhanced at least 20 percent. Orientation is improved and exposure to leading edge field minimized by disposing severa...